I tried to ran a sample of NaCl, but it didn´t have any signal.
When using IR Spectroscopy, in order for a sample to absorb infrared energy there must be a Covalent bond in between the molecules. Covalent bonds are on the same order of magnitude as infrared light frequencies and thus can absorb the infrared light. NaCL (Sodium Chloride) has Ionic bonds and does not have a Covalent bond. Therefore it cannot absorb Infrared Energy.